Multiple fuse plug



F. A. SCZHiLLER MULTIPLE FUSE PLUG Oct. 2G 1936.

Filed July 5, 193-4 Z n f m 4/.

Patented Oct. 26, 1936 teaser PATENT FF 'MULTELE FUSE PLUG Frederick A. Schiller, Newark, N. J., assignor, by mesne assignments, to Indicator Corporation, lrvington, N. 3., a corporation oi New Jersey Application July 6, 1934, Serial No. 333,945 dillaims. (oi. zoo-121) This invention relates in general to thermal fuses for uses in protecting electrical circuits, and more particularly to a plug fuse that includes means for indicating the rupture of the fuse element. The invention especially contemplates a multiple fuse plug, that is, a plug having a plurality of fuses which can be selectively connected in the circuit and used in succession as the fuses become fused or ruptured by short-circuiting or overload in the electric circuit with which the fuse plug is used.

One object of the invention is to provide such a multiple fuse plug embodying novel and improved features of construction including a body having two terminals for connection to the terminals of an electric circuit, a plurality of stationary fuses on the body, means for indicating rupture of a fuse and a movable contact means for selectively connecting the said fuses in shunt with said indicating means.

Another object is to provide a multiple fuse plug which shall comprise two coaxially and telescopically rotatable sections between the peripheries of which and mounted on one thereof is a; 25 plurality of stationary fuse elements, while the other section carries a. contact for selectively engaging the fuse elements upon relative rotation of said sections, the plug having two terminals to one of which the fuse elements are directly connected and to the other of which said contact is connected.

An important object of the invention is to provide a multiple fuse plug which shall be simple and inexpensive in construction and which shall be reliable anddurable in operation so the plug can be manufactured at a low cost and will be long-lived.

Other objects are to provide in such a fuse plug novel and improved means for mounting the fuse elements therein; to provide a multiple fuse plug of this character including means for indicating a rupture of the fuse element, and novel and improved common means for selectively connecting the fuse elements in an electric circuit and to said indicating means; and to obtain other advantages and results as will be brought out in the'following description.

Referring to the accompanying drawing in which corresponding and like parts are designated throughout the several views by the same reference characters,

Figure 1 is a vertical sectional view through a multiple fuse plug embodying my invention.

Figure 2 is a similar view taken at an angle of ninety degrees to that of Figure 1.

Figure 3 is a horizontal sectional view on the line ii-8 of Figure 2, along the surfaces of the Specifically describing the illustrated embodiment of the invention, the fuse plug comprises a body formed of two sections i and 2. The section I is generally cylindrical in shape and has a coaxial recess 3 which telescopically and rotatably receives the section 2. The recess 3 has a shoulder 4 against which the section 2 abuts and outwardly of the shoulder the section I has an opening 5 coaxial with the recess 3 through which projects an extension 6 on the section 2. The extension 6 is preferably non-circular and is fitted into a correspondingly shaped recess 1 in an operating plate 8 rotatable on the end of the section I, whereby the section 2 will rotate with the operating plate. At the end of the section l onpositethe operating plate 8' is a cap plate 9 which is connected to the operating-plate by a metal bolt [8. The cap plate 9 is held against rotation on the section I by lugs II on the cap plate fitted into correspondingly shaped notches I! on the end of the section I.

The opposite ends of the bolt III are provided with heads or upset ends which overlie the respectiveoperating plate 8 and cap plate 9, whereby the parts are held in connected relation.

The inner walls of the recess 3 are provided with a plurality of longitudinal grooves l3 which are spaced circumferentially of the recess, and in each groove is arranged one end of a fuse element 14 which passes between a lug II and notch 12 and has its other end overlying the exterior of the sleeve. A threaded metallic shell I5 is fitted over the end of the cap plate 9 and the section I in electrical contact with all fuse elements H, the shell preferably having a polygonal opening l6 fitted over a correspondingly shaped boss H on the outside of the cap plate to prevent rotation of the shell on the plug. The shell is held in position on the sleeve by pressing of the edge of the shell asat I8 into a groove IS on the sleeve. The

shell I5 is threaded to fit a standard fuse plug socket so that the plug may be screwed into such a socket, and the shell serves as one terminal or contacts for the plug while the end of the bolt 'in Figure 3.

HI serves as the other terminal or tip contact for the plug.

The section 2 has a radial slot 20 opening through the outside of the section and in which is mounted a spring contact 2| which is fixedly secured upon the bolt ID in electrical contact therewith and with its end projecting from the radial slot to contact with the fuse elements it upon relative rotation of the contact and the section I. With this construction, it will be observed that upon relative rotation of the operating plate 8 and the body section I, the inner section 2 will be rotated and by engagement of the walls of the slot 20 with the contact spring 2| will rotate the latter successively and selectively into electrical contact with various fuse elements M as shown The end of the spring contact 2| enters the grooves l3 so as to have a pawl and ratchet action, whereby the engagement of the contact with the walls of the grooves will yieldingly hold the contact in an adjusted position.

For connecting the fuse elements in circuit with a means for indicating the rupture of said elements, I have shown the shell l5 connected by a conductor 22 with a compression springbrush 23 arranged in a socket in the end of the section I and the underside of the operating plate 8 has an annular plate or ring 24 concentric with the body sections to wipe over the end of the brush 23 in electrical contact therewith. The plate or ring 24 is in turn connected by a conductor 25 to one terminal of a lamp 26, preferably of the discharge type containing a low potential mixture of inert gases, the other terminal of which is connected to a resistance 21 which is in turn connected to the bolt Ill. The lamp 3 is preferably filled with neon so that it will emit a distinctively reddish colored light when operated, and the resistance 21 is preferably of the known grid leak type and serves to prevent flow of excessive current through the lamp when a fuse element I4 is blown or ruptured. This combination of neon light and resistance is known in the art. The lamp 26 and resistance 21 are preferably mounted in an accessible position on the outer side of the operating plate 8 and may be protected from injury by a slip cover 28 which has an aperture 28 through which the lamp may be viewed. In operation the plug is screwed into a socket in the circuit to be protected and the spring contact 2| is in contact with one of the fuse elements H as shown in the drawing. The fuse element normally is in shunt with or short-circuits the lamp 26 so that the current will normally flow only through the fuse from the terminals |5, I0 and the spring contact. However, should the fuse element become blown or ruptured, the short-circuit will be broken so that current will flow through the resistance 21 and lamp 26 to cause the latter to light so as to indicate that the fuse is ruptured. It is then simply necessary to rotate the operating plate 8 to bring the spring contact 2| into engagement with another and intact fuse element, whereupon the circuit is again placed in normal position with the lamp and resistance shunted. Therefore, the fuse elements may be successively ,used and the plug will last a long time without necessity for removal or renewal, that is, the plug can be used unLl all of the fuse elements have become unfit for use. i,

From the foregoing, it' wlil be observed that my multiple fuse plug is simple and inexpensive in construction; the parts thereof are few and easy to produce and assemble. Also, the plug is simple to operate and is reliable and long-1ived.

While I have shown and described the plug as embodied in certain details of construction it should be understood that this is primarily for illustrating the principles of the invention and that many modifications and changes may be made in the details of the structure without departing from the spirit or scope of the invention.

Having thus described my invention, what I claim is:

1. A multiple fuse plug comprising a. body having two terminals for connecting in an electric circuit, a plurality of stationary fuses on said body, a lamp containing a low potential mixture of inert gases for indicating rupture of a fuse, a leak resistance in series with said terminals and said lamp, and movable contact means for selectively connecting said fuses in shunt with said lamp and said leak resistance.

2. A multiple fuse plug comprising a body including two sections one having an opening therethrough in which the other is coaxially rotatable and from one end of which the second section projects, an operating plate on said end of the first section and connected to the second section to rotate the latter, a cap plate closing said opening at the other end of the first section and held against rotation on said section, a bolt coaxial with said sections connecting said operating plate and cap plate and having one end projecting from the cap plate to form a terminal, a threaded shell on the end of said first section opposite said operating plate, a plurality of fuse elements disposed between said sections in spaced relation circumferentially of said opening each connected at one end to said shell, a contact operable by the second section to selectively engage said fuse elements and being electrically connected to said bolt, an electrical means on said operatingplate for indicating rupture of a fuse and having one terminal connected to said bolt, and a brush contact including one element mounted on said operating plate and connected to the other terminal of said electrical indicating means and another element mounted on the first section and connected to said threaded shell, so that said fuse elements short circuit said indicating means.

3. A multiple fuse plug comprising a body including two sections one having a recess in which the. other section is coaxially rotatable, a plurality of fuse elements disposed between said sections and fixed to one thereof, a spring contact carried by the other section to selectively engage said fuse elements upon relative rotation of said sections, two terminals, one connected to all of said fuse elements and the other connected to said contact, an electrical means for indicating rupture of a fuse element and having one terminal electrically connected to said spring contact, and a brush contact including two elements one carried by each of said sections, one element being connected to the other terminal of said electrical indicating means and the other element being electrically connected to all of said fuse elements so thatsaid fuse elements short circuit said indicating means.

4. A multiple fuse plug comprising a body including two coaxial relatively rotatable telescopically connected sections, one having a plurality of stationary fuse elements therein and the other carrying a contact to selectively engage said fuse elements, two terminals one connected to all of said fuse elements and the other connected to said contact, a lamp containing a low potential mixture of inert gases and a leak resistance in series with said lamp and said terminals, said lamp and resistancebeing'connectible by said contact selectively in shunt with said fuse elements, said lamp being carried by the secondmentioned section, and a brush contact including two elements one carried by each section, one

element' being connected to one terminal of said lamp and the other element being electrically connected to all of said fuse elements.

5. A multiple fuse plug comprising a body including two sections one havinga recess therein in which the other is coaxially rotatable, an operating plate at one end of the first section and connected to the second section to rotate the latter, a bolt coaxial with said sections with one endconnected to said operating plate and the other end connected to said body to form a terselectively engage said fuse elements and being electrically connected to said bolt, a brush contact including two elements one carried by said operating plate and the other carried by the first section, said elements being electrically connected respectively to said bolt and shell, a lamp containing a low potential mixture of inert gases carried by said operating plate havingone terminal connected to the first mentioned brush element and a leak'resistance connected in series with said lamp and said bolt.

FREDERICK A. SCHHLER. 

